This proposal is submitted to the Young Investigators Research Grant Program. The study has two goals: 1. the development of a method for obtaining parental occupational exposures and maternal perinatal drug ingestions, and 2. testing this method on parents of children diagnosed with acute lymphocytic leukemia between 1972 and 1979 in the State of Washington. Cases will be identified by the three major hospital control will be selected to attempt to control for any difference in recall between parents of ill and presumably well children. A general population control will be obtained by use of a random digit dialing method. Interviews will be by telephone. Occupational data will include detailed review of job-related exposures. An extensive review of maternal ingestions and exposures during the perinatal period will be done. Grouping of occupational data will be done both by job classification and actual exposure history.